The present invention relates to a folding and fixing device for changing the direction in which a belt-like conductor, such as a portion of a flexible printed circuit board, is extended and for folding the conductor and locking it in place.
For example, a flexible printed circuit board (hereinafter referred to as an xe2x80x9cFPCxe2x80x9d), used for the assembly of an electric circuit for an automobile, is generally designed so that a copper foil circuit pattern is coated with and sandwiched between insulating film. Especially when the FPC is employed to constitute a circuit portion on which electric devices, such as switches, are mounted, a lead line set, which serves as the electric wiring for these electric devices, and the electric circuit tend to be integrally formed with the circuit portion by using the FPC, wherein the copper foil circuit pattern is coated with and sandwiched between insulating films.
In the FPC, wherein the lead line set is integrally formed with the circuit portion, when the lead line set is extended linearly from a location on the perimeter of the circuit portion, multiple margins remain when an insulating film having a predetermined size is cut along the outline of the circuit pattern, wherein copper foil is sandwiched, and both the employment efficiency of the insulating film and the manufacturing yield are reduced. Therefore, in most cases, the lead line set is perpendicularly curved at the location whereat it is protruded from the perimeter of the circuit portion, and is arranged along the perimeter of the circuit portion.
However, when the distal end of the lead line set reaches a distance measured from the circuit portion of the FPC in the direction wherein the lead line set is first protruded from the perimeter before being curved, the extension of the lead line set along the perimeter of the circuit portion results in the elongation of the lead line set. As a result, even when the efficiency in the use of the insulating film and the manufacturing yield are improved, a satisfactory reduction can not be achieved in the manufacturing costs of the FPC.
In such a case, the lead line set is obliquely bent at a location in the vicinity of that it has been perpendicularly curved. Due to this folding, the direction in which the lead line set is extended is changed from one that follows along the perimeter of the circuit. Thus, even without elongating the lead line set, the distal end of the lead line set can reach a position at a greater distance from the circuit.
As is described above, when the lead line set of the FPC is to be folded, a fixing tool called a clamp, which securely grips the FPC in the bent state, is employed to prevent the recovery force of the FPC from returning the folded leading line set to its original flat state.
A conventionally well known fixing tool is the one disclosed in Japanese Patent Publication No. 4-209417A or No. 10-92238A.
The fixing tool disclosed in the former publication is constituted as follows. Through holes are formed in two portions of an FPC, which are laminated by folding the FPC and aligning the two portions with each other. Then a pin-shaped clip, which projects outward from one of two plates constituting the fixing tool, is inserted into the through holes, and the distal end of the clip is fitted into a hole formed in the other plate. The two portions of the FPC that are thus laminated by folding the FPC are thereafter sandwiched between the two plates.
The fixing tool disclosed in the latter publication is constituted as follows. A flat conductor is sandwiched between split jaws of a gripping plate assembly, and the portion of the flat conductor extending outward from the split jaws of the griping plate assembly is inserted into a cylindrical holder which is connected with the gripping plate assembly by a hinge member. Then, the holder is folded through the hinge member to change the extending direction of the flat conductor.
However, since the fixing tool in the former publication is so designed that the two aligned portions of the folded FPC are sandwiched by the two plates, due to the force exerted by the two plates used to fold the FPC is excessive, and the cutting of the copper foil circuit pattern tends to occur.
Further, since the fixing tool is so designed that the clip formed on the plate is inserted into the through holes in the FPC, when tension force is exerted on the FPC, stress accumulated by the clip is collectively applied to the portions of the FPC whereat the through holes are formed. As a result, tearing of the through holes occurs, and not only is the circuit pattern cut, but in addition, the entire insulating film is torn.
Since the fixing tool in the latter publication is so designed that the folded portion of the flat conductor is not sandwiched between the jaws of the split gripping plate, excessive folding of the flat conductor due to the force exerted by the gripping plate does not occur. In this respect, this fixing tool is preferable to the former fixing tool.
However, in order to maintain the flat conductor in the folded state, the latter fixing tool requires not only an operation whereby the flat conductor is held by the jaws of the split gripping plate, but also a tiresome operation for inserting the portion of the flat conductor that projects outward from the gripping plate into the closed cylindrical holder. As a result, an operating efficiency problem exists.
To resolve the above problems, it is one objective of the present invention to provide a flat conductor folding and fixing device that can prevent the exertion of excessive folding force or of the exertion of a collective tension force on a folded portion of a flat conductor, and that can hold the flat conductor in the folded state without requiring the employment of a tiresome operation.
In order to achieve the above object, according to the present invention, there is provided a device for folding a flexible flat conductor at a folding line, which intersects an extending direction of the flat conductor and defines a first part and a second part at both sides of the folding line as a boundary, to change an extending direction of the second part from that of the first part, and for fixing the flat conductor in the folded state, comprising:
a base piece on which the first part of the flat conductor is mounted;
a first folded piece connected to the base piece so as to be folded thereon to hold the first part of the flat conductor therebetween, the first folded piece having an edge portion which defines the folding line when the first folded piece is folded on the base piece; and
a second folded piece connected to the base piece so as to be folded on the first folded piece to hold the second part of the flat conductor, which has been folded along the folding line, therebetween.
According to the configuration, the flat conductor can be protected from being directly sandwiched and folded along the folding line by the application of an excessive folding force, and tension force is prevented from being collectively exerted on the flat conductor where it is folded along the folding line, thereby protecting the flat conductor from being cut. Further, while the tiresome process involved in the insertion of the flat conductor into and through the closed cylinder is not required, only the folding of the flat conductor along the folding line and the overlapping of the first and the second folded pieces need be performed, so that the flat conductor can be easily folded along the folding line and secured in the folded state.
In this case, preferably, the first folded piece includes a first stopper projection which is abutted against one of widthwise side edges of the second part of the flat conductor which is held between the first folded piece and the second folded piece.
According to the configuration, since the second part of the flat conductor can be prevented from moving in one widthwise direction thereof by the first stopper projection, the flat conductor on the pertinent side can be protected from being torn due to friction or to contact with the base piece, the first folded piece, or the second folded piece.
Preferably, the base piece includes a first engagement member, and the second folded piece includes a second engagement member engaged with the first engagement member when the second folded piece is folded on the first folded piece. The second engagement member is arranged so as to be abutted against the other widthwise side edge of the second part of the flat conductor which is held between the first folded piece and the second folded piece.
According to the configuration, since the second part of the flat conductor can be prevented from moving in both widthwise directions by the first stopper projection and the engagement members, the flat conductor on the pertinent side can be further protected from being torn due to friction or to a contact with the base piece, the first folded piece, or the second folded piece.
Preferably, the second folded piece includes a second stopper projection which is abutted against the other widthwise side edge of the second part of the flat conductor which is held between the first folded piece and the second folded piece.
According to the configuration, the above advantageous effect can be further enhanced.
Preferably, the edge portion of the first folded piece is chamfered.
According to the configuration, the end portion at which the flat conductor is folded relieves the degree of bend in the folded portion, so that excessive folding can be prevented, and the pertinent portion can be protected from being torn.
Preferably, the base piece and the second folded piece are connected via a hinge member. The hinge member covers the folded portion of the flat connector when the second folded piece is folded on the first folded piece.
According to the configuration, the portion of the flat conductor can be folded more precisely along the folding line, and this folded portion can be protected from contact with external objects.
In order to attain the same advantageous effects, according to the present invention, there is also provided a device for folding a flexible flat conductor at a folding line, which intersects an extending direction of the flat conductor and defines a first part and a second part at both sides of the folding line as a boundary, to change an extending direction of the second part from that of the first part, and for fixing the flat conductor in the folded state, comprising:
a base piece on which the first part of the flat conductor is mounted, the base piece having an edge portion which defines the folding line;
a first folded piece connected to the base piece so as to be folded thereon to hold the first part of the flat conductor therebetween; and
a second folded piece connected to the base piece so as to be folded on the base piece to hold the second part of the flat conductor, which has been folded along the folding line, therebetween.
In this case, preferably, the base piece includes a first stopper projection which is abutted against one of widthwise edges of the second part of the flat conductor which is held between the base piece and the second folded piece.
Preferably, the base piece includes a first engagement member, and the second folded piece includes a second engagement member engaged with the first engagement member when the second folded piece is folded on the base piece. The second engagement member is arranged so as to be abutted against the other widthwise side edge of the second part of the flat conductor which is held between the base piece and the second folded piece.
Preferably, the second folded piece includes a second stopper projection which is abutted against the other widthwise edge of the second part of the flat conductor which is held between the base piece and the second folded piece.
Preferably, the edge portion of the base piece is chamfered.
Preferably, the base piece and the second folded piece are connected via a hinge member. The hinge member covers the folded portion of the flat connector when the second folded piece is folded on the base piece.